1. Field of the Invention:
The present invention relates to a canister for capturing evaporated fuel.
2. Description of the Prior Art:
It is well known for canisters 3 and 4 as shown in FIGS. 9 and 10, to be used in automobiles for the purpose of capturing fuel evaporated in the area in which a gaseous fuel is distributed and the fuel evaporated at the oil inlet gate 2 of a fuel tank 1, and for feeding the captured fuel to be fed to an engine during its operation so as to prevent the evaporated fuel from being discharged into the atmosphere, as well as preventing fuel loss, one of which is shown in U.S. Pat. No. 3,884,204.
There are two types of canister, one of which is a vertical posture such as that shown by reference numeral 3 in FIG. 9, and the other of which is horizontal as shown by reference numeral 4 in FIG. 9 and FIG. 10, the former, being disclosed, for example, in Japanese Utility Model Unexamined Publication No. 57-123953, and the latter, for example in Japanese Utility Model Unexamined Publication No. 57-19188.
Recently, evaporated fuel of higher pressure has been employed in some automobiles, and this has led to an increase in the quantity of evaporated fuel stored in fuel tanks. As a result of this, there has been a demand for the canister of larger size. In order to enlarge the capacity of the conventional vertically mounted canister and because of the space limitation within the engine compartments of modern automobiles which allow for no increase in the diameter of the canister, it is necessary to increase the overall height of the canister.
However, since there has been a trend to lower the overall height of engine compartments even further in recent years, the limitations on the overall height of canisters has prevented the vertically mounted type canister from being enlarged in capacity. In the case of a horizontally mounted canister, there is no such problem but in this case there is another difficulty as described below.
As shown in FIG. 11 and FIG. 12, a canister case 5 formed in a cylindrical shape extending from an evaporated fuel supply port 6 to an atmospheric air port 7 with a constant diameter has an absorber 8 sealed therein, one side of which is pressed by a movable mesh tray 9 urged by a spring 10. If for some reason, the movable mesh tray 9 gets caught, gaps will be formed in among particles of fuel absorber and then the absorber 8 will settle due to vibration of the canister. As a result of this, a space 11 will be formed above the entire surface of the absorber forming a free passage between the evaporated fuel supply port 6 and the atmospheric air port 7 through which supplied fuel can pass without being captured. Thus the capacity of the canister capturing evaporated fuel will deteriorate, resulting in discharge of evaporated fuel causing air pollution. In these drawings, reference numerals 12 and 13 show filters and reference numeral 14 shows a purge port.